applications of electromagnet
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Applications of Electromagnet
1. There are many applications of electromagnets. Label and describe the figure of each
apparatus stated in the table below with its simple work-frame.
1) Electric bells
2) Electromagnetic Relays
1. When the switch is closed, the current
flow will magnetized the soft-iron core
2. The soft iron armature is pulled
toward electromagnet and hit the gong
3. At the same time, the contact will open
and stop the current flows. No
electromagnet.
4. The spring mechanism brings the
armature back to its original position5. The contacts close again and similar
pocess is repeated.
1. When the switch A is closed, a small
current flows in input circuit will
magnetized the soft-iron core
2. The soft iron armature is attracted
toward electromagnet
3. At the same time, the spring contact
closed
4. A large current flows to high voltage
circuit to operate the electrical
apparatus.
batteries
gong
soft-ironcore
springs
contact
soft-iron
armature
soft-ironcore
to high voltage
circuit
switch
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3) Telephone earpieces
4) Circuit breakers
5) Lifting Magnet
1. A varying current received from the
caller in telephone line
2. The varying current passes through
solenoid and magnetized the soft-iron
core
3. The electromagnet varies in magnetic
strength according to the verifying
current
4. The alloy diaphragm will attract to
electromagnet by varying force
5. Sound produced as compression and
rarefaction of air particles
Its operate as …………………………
…………………………………………
…………………………………………
1. When the current becomes high (ex:
short circuit) the electromagnet
strength increase suddenly
2. The iron catch is pulled toward
electromagnet
3. The spring pulling apart the contacts
4. The circuit will break and the current
flows stop immediately
Permanentmagnet
solenoid
Alloy
diaphragm
Soft-iron
core
to household
appliancesfrom mainsupply
contacts
automatic switch to breaks
circuit to open when current becomes
too large
spring
Its function to …………………………
…………………………………………
1. Opposite poles on the surface will
produces a stronger magnetic field
2. When the current is switched on, the soft
iron core is magnetized to become a very
powerful magnet
3. Its lifts up iron and steel
4. When the crane has moved to new
location, the current is switched off and
the soft-iron core is demagnetized
3. The objects will fall
move heavy objects or steel
from place to place
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3.2: Force Acting on a Current-carrying Conductor in a Magnetic Fields
1. If a current-carrying conductor is placed in a magnetic fields as shown in the experiment,
the conductor will experiences a …………………..
2. Draw the combination (called catapult field ) of two electromagnetic fields below and
show the direction of movement of the conductor.
3. Fleming’s left-hand rule can be use to determine the direction of the force acting or
the motion of the conductor.
+
N S
=
N S
PowerSupply
C-Shapeiron
Magnet
Freelyconductor
Longconductor
force
South pole
North pole
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Effect of Two Parallel Current-carrying Coils in a Magnetic Field
4. If two current-carrying conductor is placed in a magnetic fields as shown in the
experiment, the conductor will experience ………………… or ………………….. force
between them.
5. Complete the diagram for current with opposite direction flows in two parallel conductor
below:
6. Complete the diagram for current with same direction flows in two parallel conductor
below:
First Finger ( Field )
Centre Finger ( Current )
Thumb ( Thrust force )
N
repel attract
The two conductor will ……………….. to each other repel
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CoilN
S
A
B
currentD
32
4 C
1
commutator
Magnet
Carbon
brush
Turning Effect of a Current-carrying Coil in a Magnetic Field
7. Consider a current-carrying coil ABCD placed between the poles magnet as shown in the
figure below.
8. As the current flows through the coil from A to D, an ….…………….. (1) force acts on the
arm CD whereas a ……………………… (3) force acts on the arms AB according to
Fleming’s Left Hand rule.
Electrical energy Kinetic energy
The two conductor will ……………….. to each other attract
upward
downward
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CoilN
SB
A 23
4
1
current
C
D
9. Draw the catapult filed formed and draw arrows to show the movement of arms AB and
CD.
Direct Current Motor
10. Complete the four stages of the motion of DC motor below
00
Through carbon brushes Upwards
Downwards
clockwise
Degree : …………………………
Current flow : Yes / No
…………….…………………..
Arm AB : ……………………….
Arm CD : …………………………
Rotation : ………………………….
Degree : …………………………
Current flow : Yes / No
…..…………….…………………..
Arm AB : ……………………….
Arm CD : …………………………
Rotation : …………… ……….
900
Circuit broken at carbon brushes right
left
clockwise due to inertia
CoilN
S
current
N S
AB CD
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Degree : …………………………
Current flow : Yes / No
…..…………….…………………..
Arm AB : ……………………….
Arm CD : …………………………
Rotation : ……………
1800
through carbon brushes downward
upward
clockwise
CoilN
S
current
CoilN
S
current
Degree : …………………………
Current flow : Yes / No
…..…………….…………………..
Arm AB : ……………………….
Arm CD : …………………………
Rotation : …………… ……….
2700
Circuit broken at carbon brushes left
right
clockwise due to inertia
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Comparison with Alternating Current Motor
11. Complete the diagram of AC motor below:
Factors that affect the speed of rotation of an electric motor
12. The magnitude of force acting on a conductor in a magnetic increases by:
i. Increasing the current flow
ii. Stronger magnet used
13. In conclusion, the speed of rotation of the coil also can increased by:
i. …………………………………
ii. …………………………………
iii. …………….…………………………………
Increasing the current
Using a stronger magnet
Increasing the number of turns on the coils
a.c supply
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Moving Coil Ammeter
When current flows in
moving coil, magneticfield of radial magnet
will interacts with
magnetic field produce
by the coil
The force acting causes
the coil to rotate andlead the pointer to the
deflection
The hair spring willrestore the pointer bac
to its original position
The angle of deflection
is directly proportionalto the current flows in
the coil